Alloy steel



June 18, 1946. J. w. HALLEY ALLOY STEEL Filed Dec. 26, 1944 m U N 0 nw m w w 1min w o w loin n M xk *535mg Gsm T. mma N EIIS E V 5 H M w El ,m H w r 5IN 6 mwwww m m H 4 -Il P n 7 M W m UI-.H|I.N|W R R E 0 M m H H @il p M w w m.

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l JNVENToR. James Z1 Patented June 18, 1946 ALLOY STEEL t James w. Haney, chicago, n1.. asignar tu Inland Steel Company, Chicago, Ill., a corporation of Delaware Application December 26, 1944, Serial No. 569,847

The invention relates to steel and more parf ticularly to alloy steel of the low alloy type.

A number of years ago, steels of this type were developed in order to meet a. need in building relatively light-weight railway freight cars. The

7 Claims. (Cl. 148-31) 2 tensile strength substantially higher than those of steels ofthis type heretofore made and having a substantially higher impact resistance in the heat treated condition.

of this Another object is to provide a steel plain carbon steels theretofore employed in such type. which when heat treated has a much higher `car construction were relatively low in tensile yield point and higher ductility as well as a strength and yield point and placed too much much higher impact resistance than steels of weight in the car for the strengths demanded. this type heretofore made. The steel industry met this problem by provid- 10 Steels off this type, which have been on the ing low alloy steels which had substantially higher market, frequently include copper, nickel, phostensile strengths and yield points and thus perphorus and silicon in addition to carbon and mitted a reduction in weight. Other requiremanganese. Other elements are present in such ments of this type of steel were that the cost be steels but not of suicient extent orl of a charnot substantially increased and that the steel acter as to eiect problems herein considered. be ductile, corrosion resistant and readily weld- The elements named frequently fall Within the able. Such steels were intended to be used and following limits: were generally used in the as rolled condition, Per @ent although some of them could be heat treated. Carbon .01 t0 .15 Steels of this type heretofore available thus Manganese .40 to 1.00 met the needs of the industry except for one Phosphorus .05 to .13 characteristic. It was noted'that the notched 1msuman .02 to .20 pat properties of the steel were sumcient in Copper .80 to 1.30 the as rolled condition. However, the steel was Nickel .40 to 1.00 frequently heat treated by the fabricator for i 1 various purposes such as to relieve stress after Steel of the foregoing character can be heat i Welding. When certain of these steels were so treated to greatly increase the yield Point sind treated, the impact properties dropped to a loc,7 tensile strength. To illustrate such increase, the value. following exampleof actual tests is given:

Composition Treatment seel M2033 ILA, c Mn P ou N1 Lbs. per Lbaper sqJn. sq.i11. Percent Percent 0.09 0.58 0.117 1.01 een As musa 51,3211 73,480 35.8 @4.2 .ce .ze .111 1.07 .s2 1000* 11u-4ms.-- 73,180 81,920 28.0 61.2

The general object of the.v invention is there fore to provide a steel of this general type which The marked decrease in impact resistance resulting from such heat treatment is demonstrated can be heat treated to provide a yield point and by the following test results:

Composition Chsrpy impact resistance Treatment 0 Mn -P Ou Nl 75 F. 0 F. -25 F.

0.09 0.62 0.103 1.16 0.63 Astolled 48.5 35.5 31.5 .0B .62 .103 1.16 .63 1050 F.4hrsr 35.6 t5 2.5

It is to be noted that the decrease in impact resistance is particularly severe in the lower temperatures in the heat treated steel having the desired high yield point and tensile strength. In fact, the impact resistance is so low that such steel should not be employed in certain fields where its other qualities would make it suitable, as in the case of tractors and road building equipment.

I have found that such other qualities can be maintained or even bettered and the impact resistance held suiciently high by the addition of certain amounts of aluminum and molybdenum to a steel having substantially the same composition of alloying elements heretofore employed. Both the aluminum andl molybdenum may be varied in quantity but the sum of the two should be'not substantially less than 0.28%. Neither aluminum nor molybdenum alone will accomplish the desired result. I am aware of the fact that the so-called fine-grained steels contain from .01 to .08% aluminum. Such quantities do not attain the result herein sought. The aluminum content.Y herein contemplated is considerably greater.

However, if the aluminum content is on the low side, it appears to be desirable to have the sum of the elements somewhat higher, while if the aluminum is high, the sum of the two may be lower but in no case substantially less than .28%. The minimum value for the aluminum content may be as low as 0.10%, of course combined with the mined by other considerations, but is confined to the amounts suggested above for each element and the sum of the two. It is not known just why the addition of these in the quantities stated has the desired effect, but I have discovered and deilnitely established that they do have such e!- fect and that both must be present. The result the aluminum content is raised higher than 0.40%, it will have a detrimental effect on the weldability of the steel, while raising the molybdenum content above 0.35% causes an undesirable increase in hardness.

The physical properties including the impact resistance desired could possibly be obtained by a high alloy steel, butrthe cost of alloying elements and the cost of the necessary heat treatment for such steel would make the cost prohibitive. The steel herein contemplated is not to be confused with high alloy steels of such char` acter. The cost of producing the present steel may be held to'a minimum by using more aluminum and less molybdenum, since molybdenum is muchmore expensive, the molybdenum of course being held above the minimum limit stated.

To illustrate graphically the quantities of aluminum and molybdenum contemplated by the invention, I have prepared a chart shown in the drawing. In this, the values of aluminum are plotted as abscissa and the values -of molybdenum are ordinates. The larger shaded area represents the maximum range for both metals while the smaller cross-hatched area. represents the preferred range.

'Ihe enhanced physical properties of the old steel obtained by heat treatment were not avail- -able for use because of the greatly reduced impact resistance resulting therefrom. kThe new steel retains the high impact resistance after heat treament, whether such treatment is for obtaining greater physical properties or for relieving welding stresses or for other reasons. The heat treatment herein contemplated consists generally in heating to temperatures ranging from 900 F. to 1150 F. and holding it for from one to thirty-six hours, preferably followed by slow cooling. It is to be understood, however, that the invention is not limited to heat treatment at the specific temperatures and for specific periods of time stated above nor for any particular cooling rate.

The results of two tests on a heat treated steel made in accordance with the invention are shown below:

thus must be due to the cooperative effect of the two metals. The combined content o! the two elements is o Composition Charpy impact Heat treatment 0 P 0u Ni Mo 75 F. 09 F. 2l5 F.

0. 10 0. 71 ,0. 076 1.08 0. 58 0. 17 0. l5 1050 F.4 hrs..-- 53.0 36. 0 33. 0 l0 71 076 l. 08' 58 17 l5 do 57. 0 47.0 44. 0

When either the aluminum or molybdenum content is below that falling within the scope of the invention, the impact resistance is far below that desiredl as shown by the following test results:

omposltion Cbarpy impact Heat treatment O Mn P Cu Ni Al Mo F o F. 25 F.

0. 10 0'. 68 0.115 1.14 D. 62 0. 06 0. 0l 1050 F.4 hrs- 35 0 2. 0 2. 5 .0B .0W 1.18 .05 .14 .05 dn 46.0 4.0 2.0 .l0 .63 .112 1.23 .03 .06 .l0 d 30.5 3.o 2.5

ance for low temperatures in the as rolled" condition as well as after a stress-relieving heat treatment, said steel containing .01% to .15%

Composition R Yield Tensile Elong. .educ Treatment point strength in 2 tlaorn of C Mn P S Si Cu Ni A1 Mo i es' Lbs. per Lbs. per sq. in. sq. in. Per een! Per cent 0.10 0.69 0.092 0.027 0.07 1.09- 0.63 0.16 0.15 As rolled 56,680 75,840 45.0 56.

. 10 69 092 027 07 1. 09 63 16 l5 do 57, 250 76, 450 46. 5 62. 0 10 69 092 027 07 1. 09 63 16 15 l000 F -4 hrs- 70, 610 87, 200 35.0 56.1 .10 .69 .092 .027 .07 1.09 .63 16 .15 .-...do ,060 88, 400 33.0 57.7

From these, it will be apparent4 that I have 15 carbon, .40% to 1.00% manganese, .13 maxprovided a novel low alloy steel which can be heat treated to provide a high yield point and tensile strength and still maintain a high impact resistance .at all temperatures. This characteristic qualities the steel for much more extensive use than was possible with the old steel and .particularly ts it for use in the construction of tractors and road building equipment. Not only does it accomplish this resul-t but it makes it a better steel to use in many instances where the old steel seemed sufcient. For example, in the construction of freight cars, the substantial increase in impact resistance as well as the very high yield point and tensile strength is obviously beneilcial.

I claim:

1. An alloy steel having high impact resistance for low temperatures in the as rolled condition as well as after a stress-relieving heat treatment, said steel containing .01% to .15% carbon, .40% to 1.00% Inanganese, .05% to .13% phosphorus, .02% to .20% silicon, .80% to 1.30% copper, .40% to 1.00% nickel, .10% to .22% aluminum, and .08% to .20% molybdenum, the combined value of theA aluminum and molybdenum being not less than .28% the balance being substantially all iron.

2. An alloy steel having high impact resistance for low temperatures in the as rolled condition as well as after a stress-relieving heat treatment, said steel containing .01% to .15% carbon, .40% to 1.00% manganese, .05% to .13% phosphorus, .20% silicon maximum, .80% to 1.30% copper, .40% to 1.00% nickel, .10% to .22% aluminum, and .08% to .20% molybdeniun, the combined value of the aluminum and molybdenum being not less than .28%, the aluminum being suiiicient to provide a combined value near .28% when the molybdenum is at a low value, and the molybdenum being suflicient to provide a combined value somewhat higher than .28% when the aluminum is at a low value, the balance being substantially all iron.

3. An alloy steel having high impact resistance for low temperatures in the as rolled condition as well as after a stress-relieving heat treatment, said steel containing .01% to .15% carbon, .40% to 1.00% manganese, .05% to .13% phosphorus, .20% silicon maximum, .80% to 1.30% copper, .40% to 1.00% nickel, .10% to .40% aluminum, and .08% to .35% molybdenum, the balance being substantially all iron, the lower values of aluminum being used only with the higher values of molybdenum and vice versa, the combined value of the aluminum and molybdenum being not less than .28%.

4. An alloy steel having high impact resistimum phosphorus, .20% maximum silicon, .80% to 1.30% copper, .40% to 1.00% nickel, .10%l to .22% aluminum, and .08% to .20% molybdenum, the combined value of the aluminum and molybdenum being not less than .28%, the balance being substantially all iron.

5. A heat treated alloy steel containing .01% to .15% carbon, .40% to 1.00% manganese, .05% to .13% phosphorus, .02% to .20% silicon, .80% to 1.30% copper, .40% to 1.00% nickel, .10% to .22% aluminum, and .08% to .20% molybdenum. the combined value of the aluminum and molybdenum being not less than .28%, the balance being substantially all iron, the heat treatment comprising heating the steel from 900 F. to 1150 F. and holding it at such temperature for from one to thirty-six hours to increase the yield point and tensile strength without any substantial loss of impact properties at temperatures substantially below 75 F.

6. A heat treated alloy steel containing .01% to .15% carbon, .40% to 1.00% manganese, .05% to .13% phosphorus, .20% silicon maximum, .80% to 1.30%`copper, .40% to 1.00% nickel, .10% to .22% aluminum, and .08% to .20% molybdenum, the combined value of the aluminum and molybdenum Vbeing not less than .28%, the aluminum being suiiicient to provide a combined value near 45 .28% when the molybdenum is at a low value,

and the molybdenum being sumcient to provide a combined value somewhat higher than .28%, when the aluminum is at a low value, the balance being substantially all iron, the heat treatment comprising heating the steel from 900 F. to 1150 F. and holding it at such temperature for from one to. thirty-six hours to increase the yield point and tensile strength without any substan- 'tial loss of impact properties at temperatures substantially below 75 F.

'7. A heat treated alloy steel containing .01% to .15% carbon, .40% to 1.00% manganese, .05% to .13% phosphorus, .20% silicon maximum, .80% to 1.30% copper, .40% to 1.00% nickel, y.10% to .40% aluminum, and .08% to .35% molybdenum. the balance being substantially all iron, the lower values of aluminum being used only with the higher values of molybdenum and vice versa, thecombined value of the aluminum and molybdenum being not substantially less than .28%. the heat treatment comprising heating the steel from 900 F. to 1150 F. and holding it at such temperature for from one to thirty-six hours to increase the yield point and tensile strentth without any substantial loss' of impact proper- 70 ties at temperatures substantially below 'I5' l'.

JAMES W. HLLEY. 

